Rusty Russell wrote:
Was reading through page_alloc.c, and the "find smallest order" loop
assumes MIN_ORDER is 0. Easiest fix is to get rid of "MIN_ORDER" and
hence NR_ORDERS, and simplify code.
Rusty.
--- xen/common/page_alloc.c.~1~ 2005-01-11 15:35:54.000000000 +1100
+++ xen/common/page_alloc.c 2005-01-19 14:51:47.000000000 +1100
@@ -203,10 +203,8 @@
#define NR_ZONES 2
/* Up to 2^10 pages can be allocated at once. */
-#define MIN_ORDER 0
#define MAX_ORDER 10
-#define NR_ORDERS (MAX_ORDER - MIN_ORDER + 1)
-static struct list_head heap[NR_ZONES][NR_ORDERS];
+static struct list_head heap[NR_ZONES][MAX_ORDER];
This patch is broken because it replaces NR_ORDERS with MAX_ORDER,
not with MAX_ORDER+1.
#define MAX_ORDER 10
static struct list_head heap[NR_ZONES][MAX_ORDER+1];
static unsigned long avail[NR_ZONES];
@@ -220,7 +218,7 @@
memset(avail, 0, sizeof(avail));
for ( i = 0; i < NR_ZONES; i++ )
- for ( j = 0; j < NR_ORDERS; j++ )
+ for ( j = 0; j < MAX_ORDER; j++ )
for ( j = 0; j <= MAX_ORDER; j++ )
INIT_LIST_HEAD(&heap[i][j]);
/* Pages that are free now go to the domain sub-allocator. */
@@ -251,17 +249,18 @@
int i;
struct pfn_info *pg;
- if ( unlikely(order < MIN_ORDER) || unlikely(order > MAX_ORDER) )
+ ASSERT(order >= 0);
+ if ( unlikely(order >= MAX_ORDER) )
return NULL;
Why is it valid to change 'return NULL' to a failed ASSERT?
Also changing > to >= is wrong.
if ( unlikely(order < 0) || unlikely(order > MAX_ORDER) )
return NULL;
spin_lock(&heap_lock);
/* Find smallest order which can satisfy the request. */
- for ( i = order; i < NR_ORDERS; i++ )
+ for ( i = order; i < MAX_ORDER; i++ )
for ( i = order; i <= MAX_ORDER; i++ )
if ( !list_empty(&heap[zone][i]) )
break;
- if ( i == NR_ORDERS )
+ if ( i == MAX_ORDER )
if ( i > MAX_ORDER)
goto no_memory;
pg = list_entry(heap[zone][i].next, struct pfn_info, list);
--
David Hopwood <david.nospam.hopwood@xxxxxxxxxxxxxxxx>
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